8 Feb 2025 - 1.5 hours

I finished up the countersinking for the tank attach screws. I only had the top of one spar left to do so it didn't take too long to burn through.

Next on the instructions is to attack the tie down brackets. They rest across some stiffeners on the spar so there is a gap behind them that needs to be filled so you make some spacers to do just that. The get fabricated out of a single 1.25" wide aluminum bar.

You need four total spacers that are 2" long with a 1" hole in the middle of each. The best way I can figure to do this is make the holes before the pieces are cut out of the bar. I measured out the four pieces that were about 1/16" oversize in length to allow for the length that will be lost from the kerf of the saw blade. Then I marked out the centers for drilling. I did this all in the house as it was 27 degrees in the garage again so the fingers weren't very dextrous.

After getting everything marked up, I went to the drill press and drilled four centering/starting holes, then switched over to a stepped drill bit to gnaw the hole up to 1". One of the holes drifted a bit during drilling but these are just spacers and won't even be seen so this all came out just fine.

It was easy work to then cut the four parts out on the band saw. A quick hit on the scotchbrite wheel cleaned up all the edges.

With the spacers made, I switched to the tie down bracket itself and drilled the first locating hole in each bracket. One of these wandered a bit when I made the pilot hole so before enlarging to 3/16" per the plans, I used a file to walk the hole over closer to where it needs to be.

I lined up the spacers with the edge of the spar doubler. There are no specifics on where these need to be exactly, but there are holes that need to go through the meat on edge of the spacer and centering those up put the edge of the spacer almost perfectly in line with the doubler edge so I just went with that as the alignment.

The ruler gets the edges aligned and the tape holds them in place.

The tie down bracket gets aligned with a bolt through that first drilled hole and then squared to the doubler. I then clamped it in place and commenced drilling the seven 3/16" holes in each tie down bracket and spacer assembly. The spacers are pretty beefy so it took some effort/time to get those holes drilled.

Next up will be more nutplates on the spacers/tie downs!